SV-POW! … All sauropod vertebrae, except when we're talking about Open Access

Mid-Mesozoic Field Conference, Day 7: Price and the San Rafael Swell

May 9, 2014

On Monday we visited the Prehistoric Museum in Price, Utah, the Cleveland-Lloyed dinosaur quarry, and sites in the Mussentuchit member of the Cedar Mountain Formation. Many thanks to Marc Jones for the photos.

In 2010, the College of Eastern Utah became Utah State University – Eastern, and the CEU Prehistoric Museum in Price is now officially the USU Eastern Prehistoric Museum. The dinosaurs in the center of exhibit hall are being remounted. These include Allosaurus, Stegosaurus, Camptosaurus (mounted, toward top of photo), and Camarasaurus (dismounted, on floor). Most of the mounts are either real material or casts of real material from the nearby Cleveland-Lloyd quarry.

The museum has many other exhibits besides the one shown above. The paleo wing alone covers two floors, and upstairs there are great displays on Cretaceous dinosaurs from the area, including Jurassic and Cretaceous ankylosaurs, a ceratopsian, and numerous tracks.

After leaving Price we went to the Cleveland-Lloyd dinosaur quarry, which has produced over 20,000 separate elements, including the remains of something like 50-60 allosaurs. The smallest ones are hatchlings–several elements from literally cat-sized baby allosaurs are known from the quarry.

Mark Loewen (right) talked to us about how the quarry might have formed, and what it’s like to work there. On the left in the above photo you can see a bunch of disarticulated Allosaurus bones suspended above the floor on wires. These are placed to give an idea of the three-dimensional jumbling of the bones in the matrix. It is almost impossible to jacket one bone or even several without hitting others. I remember how that goes from working at the OMNH sauropod bonebed in the Cloverly–it’s almost impossible to avoid blowing through some bones just to get others out of the ground.

Here’s one of a handful of bones from the quarry with bite marks. This is the pelvis of a Camarasaurus, lying upside down, anterior toward the wall. The back end of the right ilium is heavily tooth-marked.

After Cleveland-Lloyd we stopped at a couple of sites in the Mussentuchit. I’m not going to blog about those because they are active sites that are still producing fossils. Unfortunately it is not uncommon for fossil localities on public land to be looted and vandalized by unscrupulous private collectors. I don’t want to give those a-holes any help, so I’ve deliberately not shown any photos of about half a dozen of the most interesting sites that we visited during the conference. It sucks to know cool things and not be able to tell people about them, but if I blab then I put those cool things at risk. Happily there is a lot of active research going on, including one or two projects that got hatched at this conference, so hopefully I will be able to tell some of these stories soon.

Instead, I will close this series (for now) with a shout-out to the people who convened and ran the field conference: Jim Kirkland (left) and ReBecca Hunt-Foster (middle). John Foster (right) also contributed a lot of time, energy, effort, and expertise.

Jim Kirkland is amazing. If you know him, you know that his heart is as big and outgoing as his booming voice. His knowledge of and enthusiasm for the mid-Mesozoic sites in western Colorado and eastern Utah have driven a lot of science over the past quarter century, and he shared that knowledge and enthusiasm compulsively on this trip. My head is so full of new stuff, it’s honestly hard to think. I wish I had a solid week to just digest everything I learned at the conference.

My highest praise and thanks go to ReBecca. Thanks to her hard work and organization, the whole field conference ran about as much like clockwork as something this complicated can–and when it didn’t run smoothly, like that flat tire on Saturday, she took charge and got us back on track. She was basically den mom to about 60 folks, from teenagers to retirees, from at least ten countries and four continents, and somehow she did it all with unflagging grace and good humor. The fact that she had her appendix out just two or three days before the start of the conference only cements my admiration for what she pulled off here.

One that was the best there was at what it did, but what it did best wasn’t very nice.

/Wolverine

Seriously, probably Torvosaurus. In the Cleveland-Lloyd Visitors’ Center, they had a nice display with the skulls of Allosaurus, Ceratosaurus, and Torvosaurus. Ceratosaurus had really long, really skinny teeth that did pretty much look like steak knives. Allosaurus had teeth that were still fairly laterally compressed, but not as thin, side-to-side, as those of Ceratosaurus. And Torvosaurus looked like it was trying really hard to be a tyrannosaur, with big thick teeth and a bit of that U-shaped cookie-cutter geometry to its snout.

That was the day after my camera failed, unfortunately, but I’ll see if any of my compatriots got photos, and if so, I’ll post ’em.

Well, it’s interesting. The visitor’s center–which is phenomenal by the way–had a nice big display running through something like half a dozen hypotheses that have been floated in the past. I don’t remember them all of the top of my head, but they included a watering hole drying out in a drought, a poisonous water hole, etc.

Two things stood out about Mark Loewen’s hypothesis, which I had not ever heard before. The first is that he started by running down some pertinent taphonomic data. The quarry contains something like 20,000 separate bones from 80 or 100 individual dinosaurs, of which something like three-quarters are Allosaurus (NB: you’re getting very approximate numbers pulled from the memory of a non-expert who heard basically one short popular talk on the quarry). Almost all of the elements are disarticulated, although in a few cases a small group of bones–like, say, part of a limb or tail–has been found articulated. Of these 20,000 bones, maybe a dozen or two have tooth marks. That is a tiny proportion, especially if this is supposed to be a predator trap in the normal sense. Also, hardly any of the bones are trampled–again, something in the low dozens, out of 20,000. Not what you’d expect if animals were dropping like flies in a static collecting area over an extended period of time. So you’ve got 20,000 almost perfectly-preserved bones, with articulated elements, bite-marked elements, and trampled elements all present but at miniscule proportions–roughly 1 or 2 in 1000 for each of those categories.

The bones are pretty evenly mixed in three dimensions through about a vertical meter of mudstone, which is capped by a very thick, extremely hard layer of limestone. The limestone suggests a lake. To Mark, the even mixing of the bones, with robust and fragile elements intermixed and almost no damage, suggests a single depositional event. He thinks probably a flood. He told us about seeing a dozen dead cows floating in an eddy in a flooded field one time, and also about finding fish in the Green River Formation that had completely disarticulated but were still mostly in one pile, like the allosaur bits in the photo above.

Here’s the second thing I liked about Mark’s hypothesis: he didn’t try to explain everything. Someone asked him about why, if it was a flood, there were so many allosaurs compared to everything else. He thought that perhaps a whole pack of allosaurs had gotten caught in the same flood, and that’s why there were so many of them, but he also straight up said that he didn’t know–the question of how that specific group of animals came to be dead at the same place and time was at least potentially a separate question from how they all came to be buried as they are. He was working from geology and taphonomy, which in this case seem to be informative about how the animals were buried than about how they had died. I really liked that breakdown, like “Here’s the part of the story that I have evidence for, and here’s the part of the story that’s still mysterious.” It made me wonder how many other seemingly intractable problems in paleobiology (and science more generally) actually have tractable parts embedded within them, if only we could take them apart into their component bits.

It made me wonder how many other seemingly intractable problems in paleobiology (and science more generally) actually have tractable parts embedded within them, if only we could take them apart into their component bits.

That is an excellent question, and one that — now I’ve heard it baldly stated — leaves me wondering why I’ve never heard this articulated before.

As you know, I am a computer programmer by profession, and one of my old email-signature tag-lines was this pithy observation from Brian Kernigan: “Controlling complexity is the essence of computer programming”. It’s absolutely spot on. Modern computers are ferociously complex, and it’s flatly impossible to understand all that complexity at once. What we have to do instead is control it, by coming up with ways to think about only a small part of the problem at once. That’s the root of almost every programming buzzword you can think of: abstraction, encapsulation, object orientation, APIs, functional decomposition. It’s all about making ways to ignore 99% of the problem at any given time, and so to concentrate on the 1% you’re interested in.

Why don’t we apply this technique to more areas of endeavour? Maybe it’s just a habit of thought. When I program, I think like a programmer; when I do palaeo, I think in the way that all the papers I’ve read have taught me is how palaeontologists think. Perhaps we can do better. Separating “how did they die?” from “how were they preserved?” is a fine first example.